Abstract: The fundamental rheological properties of gum from seed of Nicandra physaloides (L.) Gaertn and the effects of factors, such as concentration(g/L, the same below), metal ions, sugar, standing time, pH value, temperature, freezing-thawing treatment on rheological properties were researched with Brook field RVDV-Ⅲ rheometer. Results indicated that gum solution had typical shear-thinning property, and the rheological properties were influenced by temperature, shearing rate, pH value, freezing-thawing treatment, etc. It was found that the gum solution investigated behaved as non-Newtonian shear-thinning fluid. With the increase of gum concentration(above 2 g/L), the consistency coefficient increased while the viscosity index decreased. The thixotropic response became stronger when gum concentration was increased. The increasing of temperature could reduce the viscosity of gum and the temperature dependence of η could be expressed by a relation of the Arrhenius equation. At pH value 3, the highest viscosity of aqueous solution (5 g/L) was 0.152 Pa·s, while strong acid and strong base resulted in a decrease in viscosity. Bivalent metal ions obviously improved the viscosity of gum solution, and the thickening effect was positively correlated to the concentration of metal ions. At the same concentration, the thickening effect of sucrose excelled glucose.

Key words: Nicandra physaloides(L.) Gaertn seed gum, rheological property, metal ion, sugar